3. The right sized energizer
Undersized energizers are another common mistake, Gerrish says. His guideline: 1 joule of output per mile of fence, regardless of how many strands of wire.
It works well, considering a typical operation has several different types of fence: a 4- or 5-strand high-tensile perimeter fence and some 1- or 2-strand interior fences. If there is a total of six miles of fence, it will require a minimum of a 6-joule energizer.
“You're pretty well covered if you plan for 1 joule per mile of fence,” Gerrish says.
Mohr recommends using a low-impedance energizer, with a low-amp fuse. “The larger the energizer, the smaller the voltage,” Mohr says, because larger energizers are apt to power through more vegetation and short out. He considers 7,000-8,000 volts high for an energizer.
“Grounding is 99% of the electric fence,” Mohr states.
Gerrish uses the rule of thumb: 3 ft. of ground rods per joule of energizer output. So if the fence is using a 6-joule energizer, it would call for 18 ft. of ground rods. “Typically this would be three, 6-ft. ground rods, spaced at least 10 ft. apart,” Gerrish explains.
Spacing is key. Gerrish explains that a ground rod is essentially an antenna receiving electrons flowing through the soil and back to the energizer, completing the circuit. Ground rods can also interact with a given volume of soil. So if three ground rods are driven into the ground 6 in. apart, in essence they act as one ground rod because of the volume of soil they interact with.
Mohr points out that most people will put in three ground rods near the energizer. He encourages people to space ground rods throughout the whole network of fencing. It's especially necessary if the average rainfall of the fenced area is less than ideal for proper grounding.
Copper makes the best type of ground rod, but it is expensive. Which is why most fencing companies use an insulated galvanized lead-out wire on energizers. “If you have a copper ground rod, you need to run a copper wire to the energizer that it's grounding,” Gerrish says.
Likewise, if there's galvanized wire in the electric fence system, keep everything galvanized. Mohr strictly recommends nothing but 12.5-ga. galvanized wire, galvanized ground rods and galvanized connections. He notes, too, that a galvanized ground clamp won't have corrosion problems that a copper connection would have in six months.